1. Field of the Invention
The present invention relates to an arrhythmia detecting apparatus suitable for detecting arrhythmia at rest and during daily activity, from the pulse.
2. Description of the Related Art
The pulse generated by the contraction of the heart may be obtained in the form of a pulse wave (pulse waveform). This pulse waveform can be broadly separated into a "principal wave", which arises from the contraction of the heart which causes blood to be sent into the arteries, and a "dicrotic wave", which derives from closure of the heart valve. In a healthy individual, there is a regular repetition in the contraction of the heart, such that the pulse waveform exhibits a constant rhythm.
However, when the heart is weak due to an abnormality in the circulatory system, an arrhythmic pulse may occur. While these types of disorders in the pulse (hereinafter, referred to as "arrhythmia") can be caused by smoking, they are also frequently seen in cardiac diseases such as cardiac valve disease, myocardial infarction, cardiomyopathy and so on. Accordingly, arrhythmia detection would be useful for the diagnosis of some abnormalities in the circulatory system.
The danger of bradycardia (in which the pulse rate is less than 40 beats/min), caused by symptoms of complete atrioventricular block or Adums-Stokes syndrome, is well known. Moreover, it is also known that symptoms of sick sinus syndrome cause bradycardia or tachycardia (in which the pulse rate is 150 beats/min or more). Further, extrasystole can cause intermittent pulse (arrhythmia), so that its occurrence during exercise may be considered quite dangerous. Thus, in view of these circumstances, considerable focus has been placed on detection of arrhythmia.
It has been the conventional to detect arrhythmia such as described above by employing an electrocardiogram in which electrodes are attached to the subject's chest, and an electrocardiac potential is detected via the electrodes.
An electrocardiography is a large device, and requires the attachment of electrodes to the subject. Accordingly, the subject's movements are restrained since he cannot leave the examination room for the duration of procedure. While portable electrocardiogram recording devices have been developed in recent years, these too are problematic since they are difficult to use, and do not enable a person without specialized knowledge to detect arrhythmia on his own easily. In other words, until now, it has not been possible to detect accurately arrhythmias during in one's normal daily activities.